Horizontal or vertical? I was testing problems with vertical platforms (which David has fixed for the next build)... I honestly didn't even think to try horizontal ones.
Vertical platforms. Actually, i just checked it again just by loading up the old version of GUYMAN HERO in 99.8 (if you didn't delete it you probably have that version too, the one i PMed to you just copy and paste the player to the really frustratingly hard platform-y screen and test it on the first platform) and the jumping problem happens even when the player is standing on a stationary platform.
It also seems like now there is a pixel's worth of distance between the player and the platform. Sometimes. Sometimes there isn't. That was never there before either.
If you could check too, that would be great.